This invention relates to a device which employs vortex shedding for measuring the relative speed between the device and a surrounding fluid.
Such devices may be used to determine the relative speed of a body through a fluid, as in a ship's log, or to determine the relative speed of a fluid past a stationary body, as in a fluid flowmeter. The relative speed is determined from measurements of the frequency at which vortices are shed from an obstruction in the fluid stream. The term "fluid" employed herein is hereby defined to include both liquids and gases.